Refactor email template handling and namespaces

Updated namespaces for email template files and improved
class structures. Removed the Language parameter from
EmailTemplateQuery. Added ReadEmailTemplateQuery and
ReadEmailTemplateResponse with updated parameters.
Introduced UpdateEmailTemplateCommand for template updates.
These changes enhance clarity and functionality in the
email template management system.

EnvelopeGenerator.Application/EmailTemplates/Commands/Update/UpdateEmailTemplateCommand.cs

@@ -0,0 +1,18 @@
+namespace EnvelopeGenerator.Application.EmailTemplates.Commands.Update;
+
+
+/// <summary>
+/// Befehl zum Aktualisieren einer E-Mail-Vorlage.
+/// </summary>
+/// <param name="EmailTemplate">
+/// Die Abfrage, die die E-Mail-Vorlage darstellt, die aktualisiert werden soll.
+/// </param>
+/// <param name="Body">
+/// (Optional)Der neue Inhalt des E-Mail-Textkörpers. Wenn null, bleibt der vorhandene Inhalt unverändert.
+/// </param>
+/// <param name="Subject">
+/// (Optional) Der neue Betreff der E-Mail. Wenn null, bleibt der vorhandene Betreff unverändert.
+/// </param>
+public record UpdateEmailTemplateCommand(EmailTemplateQuery EmailTemplate, string? Body = null, string? Subject = null)
+{
+}